题目内容
两个白炽灯泡,一个标有“220V 100W”,另一个标有“220V 60W”.假如灯丝的电阻不变,先把它们串联起来接到220V电源上,再把它们并联起来接到220V电源上.以下说法正确的是( )
A.串联比并联消耗的总功率大 |
B.并联比串联消耗的总功率大 |
C.串联时60W灯泡消耗的电功率较大 |
D.并联时100w灯泡消耗的电功率较大 |
BCD
试题分析:当两灯泡并联在220V的电压上,则两灯泡都能正常发光,所以消耗的电功率为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150907347767.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150907394582.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150907456972.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509075961030.png)
当两灯泡串联在220V的电压上时,消耗的总功率为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241509076431357.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150907784480.png)
综上所述BCD正确,
点评:关键是根据串并联电路的特点分析
![](http://thumb2018.1010pic.com/images/loading.gif)
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